1. Field of the Invention
This invention relates generally to pipe assemblies and more specifically to encasing a pipe within another pipe in a multiple-wall pipe structure.
2. Art Background
Pipes comes in many different shapes and sizes for a myriad of functions. One particular class of pipes relates to multiple-wall pipes having an inner pipe encased within one or more outer pipes. The purpose of such multi-wall pipe usually stems from a need to provide some form of insulation between the fluid carrying medium and the outside environment.
In a double-wall pipe, the fluid medium travels within the confinement of an inner pipe or tube. An outer pipe encases the inner pipe in such a manner as to shield the inner pipe from the outside environment. An insulation barrier normally exists between the inner pipe and the outer pipe. The amount of insulation primarily depends upon the distance separating the exterior wall of the inner pipe from the interior wall of the outer pipe and also the material used as the insulator.
In a double-wall chimney pipe intended for use as an exhaust medium for the device such as a stove, oven, heater or fireplace, heated exhaust gases, as well as solid particles generated by the fuel oxidized in the device, travel through the inner pipe to the outside environment, which is usually the atmosphere. Mostly due to convection the inner pipe will increase significantly in temperature. The insulating material between the inner pipe and the outer pipe must reduce the temperature present at the exterior wall of the outer pipe from that present at the outer surface of the inner pipe. In many instances, flammable mateiral, such as wood which is used in residential buildings, make direct contact or are in near proximity to the pipe assembly and safety reasons require isolation as well as insulation of the heated inner pipe.
When the insulating material consists of solid matter, the solid structure of the material may provide the support necessary to hold the inner pipe in a fixed position within the outer pipe. However, when gaseous material, such as air, provides the insulating medium, some mechanical means are necessary to hold the inner pipe in a fixed position within the outer pipe.
Prior art double-walled chimney pipes used mechanical brackets which hold the inner pipe in place. Such a prior art bracket requires welds, screws, rivets or the like for mounting it to the inner and outer pipes. Hence, a prior art bracket will usually require extraneous hardware components, such as screws and rivets, and will always require an assembly step of welding, screwing, riveting, or the like during the manufacturing process of the chimney assembly.
Inasmuch as most chimney systems entail the need for long sections of pipe, as well as a requirement for bends in the system, flexibility requires manufacturers to sell chimney pipes in sections. Manufacturing of appropriate lengths of pipe, as well as elbows, will allow a builder to select the necessary sections to complete the builder's required chimney system. However, any effort exerted by a worker in mounting a bracket to a chimney pipe detracts from the optimum efficiency of the chimney system construction. A rapid assembling technique allows workers to construct a chimney system in a minimum amount of time.
As will be described, an improved pipe spacer is provided which has particular utility for use in fireplace chimney applications.